- Title
- Microhabitat and biotic structure of stromatolite formations
- Creator
- Weston, Ross-Lynne Alida
- Subject
- Stromatolites
- Subject
- Microbial mats Sedimentary structures
- Date Issued
- 2018
- Date
- 2018
- Type
- Thesis
- Type
- Masters
- Type
- MSc
- Identifier
- http://hdl.handle.net/10948/17493
- Identifier
- vital:28358
- Description
- Stromatolites are among the oldest types of microbial formations. In contrast to their ancient counterparts, many modern marine stromatolites have a coarser internal structure and host a diverse eukaryotic community. Different mesofabric structures are found within stromatolite formations which may provide microhabitat opportunities for organisms. Therefore, the first aim of this study was to investigate how the microalgal (including Bacillariophyta, Chlorophyta and cyanobacteria) community contributes towards the differences observed amongst mesofabric structures in terms of depth profiles and layering at representative stromatolites forming along the Port Elizabeth coastline in South Africa. The second aim was to investigate how the invertebrate community changes between mesofabric types. This was achieved by comparing the proportional abundances of each of the major microalgal classes between the different mesofabric types and depth profiles. Additionally, the invertebrates found within samples collected were identified and counted. These were related to site and environmental characteristics using multivariate modelling. Clear variability in terms of proportional abundance was apparent between microhabitats and with depth. Coarser, more-bioturbated types had a higher bacillariophyte biomass than smoother types. Invertebrate abundance was generally higher in coarser mats. However, one of the finer, well-laminated types had surprisingly more invertebrates than expected, but only in summer. The changes in microalgal and invertebrate community distribution varied seasonally. More microalgae were found in summer and more invertebrates were found in winter. Microalgae distribution was driven by mesofabric features whereas invertebrate distribution was attributed to resource changes. The implications of this study are in terms of the role of microalgae as ecosystem engineers in driving microhabitat differences. The microhabitats provide opportunities for colonisation by invertebrates.
- Format
- iv, 61 leaves
- Format
- Publisher
- Nelson Mandela University
- Publisher
- Faculty of Science
- Language
- English
- Rights
- Nelson Mandela University
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